Dip tubes for emptying the contents of tanks are generally constructed by modifying commonly used plumbing pipes and fittings, and gluing these pieces together to produce a structure with an opening that is near the floor of the tank. The dip tube is often provided with an opening that is substantially oval because such geometry of the opening reduces the likelihood of clogging. Moreover, it is helpful to allow the dip tube to rotate about the tank so that the dip tube can facilitate connection with neighboring pipes or tubes that approach the dip tube assembly. However, the rotation of the dip tube is restricted because the tank walls or hull often gets in the way of the rotation inside the tank. Thus, there is a need to provide a dip tube that overcomes the above limitation while providing the same benefits.